In recent years, new high-speed communication service called LTE (Long Term Evolution) has been expected to become standards for the communications of mobile stations such as mobile phones, and LTE-Advanced systems, which are an improved version of LTE systems, have been under discussion at the 3GPP (3rd Generation Partnership Project).
LTE-Advanced systems are intended also as IMT (International Mobile Telecommunication)-Advanced systems, which are an improved version of IMT-2000 systems and have been decided to be given consideration at the ITU-R (International Telecommunication Union Radio communications sector).
Typical examples of IMT-2000 systems are W-CDMA (Wideband-Code Division Multiple Access), CDMA one, and WiMax (Worldwide Interoperability for Microwave Access).
For LTE-Advanced systems, consideration is being given, based on LTE systems, to widening of uplink and downlink bandwidths, uplink MIMO (Multiple Input Multiple Output), MBMS (Multimedia Broadcast Multicast Service), and introduction of a relay station (repeater station) between a wireless base station and a mobile station.